Well after reading this....my best guess would be the map sensor.

 

Sounds logical. I'm reading a Chilton's for this truck. It is almost helpful.

 

Found this item. Interesting. http://www.wellsmfgcorp.com/pdf/counterp_v6_i1_2002.pdf It addresses similar problem on 93 3.9L. I had discoveredslack in my rotor shaft and had asked a factory mechanic about it. He said that they had been taught that the gear should be replaced if the slack exceeds three degrees. I estimate my rotational slack to be more than that. However, the mechanic steered me away from doing that, suggesting that the problem was more likely to be electrical.

I had no more luck finding parts in stock today than Saturday. Auto Zone said that if I bring the old parts in, they can test them. That is great. No sense in replacing good parts.

The wife said I should ask you for all the parts that you took off, since most of them were probably still good!

 

HELP!! I was given a 1992 Dodge D-150 3.9 1/2 ton. I was told that all it needed was a fuel pump... Needless to say alot of other things have shown up. Apparently it sat for awhile. Once I finally could ante up for a fuel pump. then I started trying to eleminate the rough running and bucking. Keep in mind that I am a full time student with limited income. after the fuel pump I then changed the spark plugs, wires, distributor cap, rotor and cleaned the injectors and replaced the o-rings, Now my mechnic says that the o2 sensor needs to be replaced. thats $60. I can't afford now and I have no transport for school. I have limited tools and means, can any one give a lady a break? Did the throttle sensor do the trick?

 

I wasn't sure if you were asking me or erock92kota, so I hope neither of you will be offended if I jump in with my two cents worth.

You have gone down pretty much the same road as I except for the fuel pump. Of all of the things that I tried, replacing the throttle sensor was the least effective measure. Of course, if your unit is bad, it may make a major difference. Can you take it off and carry it to a parts dealer who has the tools to check it? Places like Auto Zone and Advance Auto may be able to help you. It is not hard to remove, but you will need the correct size torx driver.

My engine had 108,000 miles on it and the timing chain was stretched badly. Also the oil pump drive shaft and bushing were badly worn. Replacing those items made the biggest improvements of all of the changes that I made. Those items will require more than just the average skills and experience and require special tools. Remove the distributor cap and have someone turn the crankshaft back and forth. Watch to see how far the bottom pulley has to be turned before the rotor button starts to move. You can expect it to have about 5 degrees slack or more. Mine had about 15 degrees slack and was way overdue to be changed. Next, grasp the rotor button and twist it back and forth to check for rotational slack. Up to 3/16" movement is o.k.. Not ideal, but o.k.. Anymore than that and the oil pump/distributor shaft and bushing will need to be changed. If that is the case, your motor is probably backfiring alot. If it is not backfiring, those parts are probably o.k., but I read that your motor is bucking, so I suspect you may have this problem too.

My truck still isn't 100%,but itis much better. I'm thinking o2 sensor myself. It's $55 at Auto Zone. If your mechanic quoted you $60 parts and labor, that's a real deal - when you can afford it. That's cheaper than carrying it to the dealer and having them check it, plus when its done you have a new 02. I have read that it should be changed every 60,000 miles anyway.

Since my truck isn't a daily driver, I haven't felt the pressure to finish correcting it. I think it is about 95% right. It is very usable now, but I still need to work on it some more.

I have been where you are now with school expenses and all and I know it doesn't solve your problem to tell you this, but if you can get your truck running for four or five hundred dollars,
that is much less than it would cost to go buy a good running vehicle. Once it is running, you won't get good gas milage out of that vehicle, maybe 16 mpg, but that is still cheaper than a car payment.

Good luck.